Buggy code:
public class Utils { private final String TAG = Utils . class . getName ( ) ; private static Utils myInstance ; private LocaleUtils localeUtils ; private Context context ; private Typeface typeface ; private SharedPreferences prefs ; private List < EventEntity > events ; private PrayTimesCalculator prayTimesCalculator ; private Map < PrayTime , Clock > prayTimes ; private String cachedCityKey = "" ; private CityEntity cachedCity ; private Utils ( Context context ) { } public static Utils getInstance ( Context context ) { } public String shape ( String text ) { } public String getString ( String key ) { } public String programVersion ( ) { } private void initTypeface ( ) { } public void setFont ( TextView textView ) { } public void setFontAndShape ( TextView textView ) { } public void setFontAndShape ( PreferenceViewHolder holder ) { } public void setActivityTitleAndSubtitle ( Activity activity , String title , String subtitle ) { } public CalculationMethod getCalculationMethod ( ) { } public int getIslamicOffset ( ) { <START_BUG> return Integer . parseInt ( prefs . getString ( PREF_ISLAMIC_OFFSET , DEFAULT_ISLAMIC_OFFSET ) ) ; <END_BUG> } public Coordinate getCoordinate ( ) { } private char [ ] preferredDigits ; private boolean clockIn24 ; public boolean iranTime ; public void updateStoredPreference ( ) { } public boolean isPersianDigitSelected ( ) { } public void setTheme ( Context context ) { } public boolean isWidgetClock ( ) { } public boolean isNotifyDate ( ) { } public int getAthanVolume ( ) { } public String getAppLanguage ( ) { } public String getTheme ( ) { } public String getSelectedWidgetTextColor ( ) { } public PersianDate getToday ( ) { } public Calendar makeCalendarFromDate ( Date date ) { } public String clockToString ( int hour , int minute ) { } public String getNextOghatTime ( Clock clock , boolean changeDate ) { } public String getPersianFormattedClock ( Clock clock ) { } public String getPersianFormattedClock ( Calendar calendar ) { } public String formatNumber ( int number ) { } public String formatNumber ( String number ) { } public String dateToString ( AbstractDate date ) { } public String dayTitleSummary ( PersianDate persianDate ) { } public String getMonthName ( AbstractDate date ) { } public List < String > getMonthsNamesListWithOrdinal ( AbstractDate date ) { } public String getWeekDayName ( AbstractDate date ) { } public void quickToast ( String message ) { } public int getDayIconResource ( int day ) { } private String convertStreamToString ( InputStream is ) { } private String persianStringToArabic ( String text ) { } private < T > Iterable < T > iteratorToIterable ( final Iterator < T > iterator ) { } public List < CityEntity > getAllCities ( boolean needsSort ) { } public CityEntity getCityFromPreference ( ) { } private List < EventEntity > readEventsFromJSON ( InputStream is ) { } public List < EventEntity > getEvents ( PersianDate day ) { } public String getEventsTitle ( PersianDate day , boolean holiday ) { } public void loadApp ( ) { } public boolean isServiceRunning ( Class < ? > serviceClass ) { } public void loadAlarms ( ) { } public void setAlarm ( PrayTime prayTime , Clock clock , int id ) { } public void setAlarm ( PrayTime prayTime , long timeInMillis , int id ) { } public Uri getAthanUri ( ) { } public void changeAppLanguage ( String localeCode ) { } private void changeCalendarLanguage ( String localeCode ) { } public String loadLanguageFromSettings ( ) { } public void copyToClipboard ( View view ) { } private static class CopyToClipboard { @ TargetApi ( VERSION_CODES . HONEYCOMB ) public static void copyToCliboard ( CharSequence text , Context context ) { } } public SeasonEnum getSeason ( ) { } public List < DayEntity > getDays ( int offset ) { } }

Fix:
return Integer . parseInt ( prefs . getString ( PREF_ISLAMIC_OFFSET , DEFAULT_ISLAMIC_OFFSET ) . replace ( "+" , "" ) ) ;